1. Field of the Invention
The present invention relates to a TV, and more particularly, to a method for controlling channel tuning of a digital TV.
2. Background of the Related Art
An analog TV receiver has been commercially used in various types from a small sized TV of 14 inches to a projection TV of 60 inches or greater.
However, the analog TV has several problems in accordance with the trend of a large sized screen and high function. First, when a user views a large sized TV in an analog mode such as NTSC, PAL and SECAM, the user suffers deterioration of picture quality. Second, channels assigned for TV broadcasting are limited to 80 including ultra high frequency channel bands. Actually available ground wave channels are no more than half of the broadcasting channels due to interference between adjacent channels. Third, the analog TV has limitation as a unidirectional medium. In other words, TV has had only a function as a receiving medium but will require a bidirectional function in the future with the spread of personal computer and Internet. Finally, the analog TV has a problem in that its market is completely congested. In other words, since almost every family has two or more analog TVs currently, demand of the analog TV is not expected any longer.
Therefore, to solve the problems of the analog TV market, a digital TV has been developed.
A general digital TV will be described with reference to FIG. 1.
As shown in FIG. 1, the digital TV includes a front end unit 10 for inputting a digital radio frequency (RF) signal and a back end unit 20 for signal processing.
The front end unit 10 includes a tuner/link unit 11 for demodulating the RF signal received through an antenna. The back end unit 20 includes a transport protocol (TP) divider 21, a microprocessor 22, a video/audio decoder 23, an NTSC/PAL encoder 24, an on screen display (OSD)/graphic accelerator 25, a peripheral device processor 26, IEEE1394 27, a traffic controller 28, a DRAM 29 for application software data, and an SRAM 30 for OSD data. The TP divider 21 digitally processes the demodulated RF signal and outputting the digitally processed signal through a monitor and a speaker.
The operation of the aforementioned digital TV will now be described.
A transport packet QPSK modulated by a transmitter is input to the tuner/link 11 thorough the antenna.
The transport packet corresponding to a broadcasting program tuned by a user using a remote controller is divided into audio data, video data, and programmable system information (PSI) by the TP divider 21 under the control of the microprocessor 22 through I2C bus.
The audio data are output to the speaker through the video/audio decoder 23 and an amplifier (not shown) while the video data are output to RGB, Y/C, and CVBS through the video/audio decoder 23 and the NTSC/PAL encoder 24, so that the user can view the video data through a cathode ray tube (CRT) or a flat panel display (FPD).
At the same time, the PSI, i.e., user data, caption data, teletext data, broadcasting guide data, and OSD data, are displayed on a screen, together with the audio signal, through the OSD/graphic accelerator 25.
Meanwhile, the peripheral device processor 26 accesses a remote controller, a GPIO, a smart card, and a modem through an external input terminal so as to interface various broadcasting data and user data.
At this time, the traffic controller 26 controls a flow of a digital signal and a memory access operation of the DRAM 29 and the SRAM 30.
The aforementioned digital TV improves a video quality of the analog TV so as to provide clearer picture quality two times than the analog TV. Since the digital TV has no interference between adjacent channels, channel regions not used conventionally can be used.
According to a program service information protocol (PSIP) which is a broadcasting specific information standard for providing detailed information on a broadcasting program from an advanced television service committee (ATSC) which is a US digital TV standard suggested in November, 1997, a high definition (HD) digital broadcasting program or four standard definition (SD) digital broadcasting programs can be transmitted to a physical channel, i.e., a channel of 6 MHz band. Accordingly, the digital TV has an advantage that can provide various services of several hundred types.
Furthermore, since the digital TV provides bidirectional services to enable Internet service, home shopping service, and home banking service, it is likely to replace an analog channel with a digital channel in the near future. Therefore, it is expected that demand of the digital TV will increase in the future.
The PSIP standard will now be described in more detail. For channel allocation, there are a major channel number and a minor channel number. The major channel number represents a channel number allocated to a band of 6 MHz used for a ground wave broadcasting while the minor channel number represents a channel number allocated to a digital service channel transmitted through a band of 6 MHz.
On the other hand, the ATSC gives each broadcasting station a specific value for the major channel but allows each broadcasting station to manage the minor channel so that the minor channel number can be changed at any time.
The related art digital TV has a problem in that the user cannot tune a corresponding channel if the user does not directly request the minor channel because an easy interface for tuning of the major-minor channel is not provided.